The subject matter disclosed herein relates to an apparatus for sewing sections of material and, more particularly, to an apparatus for sewing vehicle interior components
Currently, most stitching found in an automotive interior is of the functional variety, wherein two or more pieces of material (leather, vinyl, TPO, cloth, etc) are cut from a pattern and sewn together (cut-n-sew) prior to being wrapped around a component such as a seat cushion, head rest, arm rest, console lid, instrument panel substrate, etc. Such functional stitching is very labor intensive and is normally used only where required on low and mid-class vehicles. Functional stitching on decorate components such as instrument panel retainers and door panels has typically been restricted to higher class vehicles due to cost.
In recent years, automotive original equipment manufacturers (OEMs) have shown an interest in applying the “stitched” look to more vehicles over a wider range of price classes. A simulated non-functional stitch has been used in some applications; however, the ability to offer a simulated stitch in a contrasting color is not production feasible at this time. Additionally, more OEMs are requested that a real or “live” stitch be used on decorate components to provide the look and feel of a true cut-n-sew component.
Thus, it is desirable to provide a live, non-functional stitch on decorative automotive trim components without using costly cut-n-sew technology. One method of providing this feature is to stitch a pattern on an unformed single or multilayer construction of trim material and wrap the sewn trim sheet around a preformed/precut substrate. However, as the part complexity and size increase this becomes impractical as unformed trim material can only be applied to relatively flat surfaces.
Another option includes stitching a pattern on a preformed single or multilayer construction of trim material and bond the sewn trim preform to a preformed molded substrate. However, this requires that the size and shape of the preformed & stitched skin match that of the molded substrate nearly perfect. This method may require that all surfaces in die draw have adequate draft in order to accommodate nesting without damage to the preform. All undercuts using this method require automated or manual edge wrapping to finish.
A third method includes stitching a pattern on a flat or relatively flat single or multilayer trim & substrate component construction. This method eliminates the fit and finish issues associated method discussed above, but is limited by the ability of the sewing machine to reach confined areas of the part while possessing the capability to drive a needle through trim and substrate material of the component. Likewise, any backside features (ribbing, bosses, etc.) required for component structure or attachment cannot be located in the area directly behind/beneath the stitch path.
A fourth method includes stitching a pattern on a preformed single or multilayer trim & substrate component construction. The apparatus for performing this method consists of the use of a chain stitch sewing machine that uses an awl on the upper portion of the head to penetrate the trim and substrate of the interior component. After the awl exits the hole it produced in the component a needle with hook protrudes through the hole from the lower arm of the machine to grasp the thread held in position by the thread tensioner arm. Once hooked, the thread is pulled through the hole and through the loop from the previous stitch. The needle also advances the part to the next point of awl penetration as it pulls the thread down through the hole. The needle then advances to the hook position once again while the awl is engaged with the part so the part does not move and needle can move through the newly formed hole without hesitation once the awl exits the part.
However, if a small thru-plane radius must be sewn with the needle & awl design as described above, it becomes challenging to accommodate needle removal from the part as well as ensure proper alignment with the subsequent hole produced by the awl. As a result, needle damage or part mis-location during sewing may occur.
Accordingly, while existing sewing apparatus for vehicle interiors have been suitable for their intended purpose the need for improvement remains, particularly in providing a sewing apparatus that allows for a cut-n-sew appearance in a cost effective manner.